Colored bituminous materials a method of obtaining them and a coloring composition for carrying out the method

ABSTRACT

The invention consists of a method of obtaining colored bituminous materials consisting of: 
     applying onto at least one surface of the material to be treated, an aqueous coloring composition based on pigments and resin with a restricted range of solubility, 
     drying the material coated with the coloring composition 
     then impregnating it with bitumen.

FIELD OF THE INVENTION

The invention relates to coloured or pigmented bituminous materials,notably used as covering, siding or sealing materials.

BACKGROUND OF THE INVENTION

A method for the colouring or the pigmenting of bituminous materials hasalready been described in French Patent No. 2 352 929.

It consists of applying a colouring composition onto a fibrous material,then drying the composition and then impregnating the fibrous materialcoated in this way, in a bath of hot bitumen.

The colouring composition has a high water content and comprises resin,pigments, a thickening agent, a dispersing agent and possibly fillers.

This method allows one to obtain coloured bituminous materials whoseresistance to ageing is better than that observed with materialsobtained by known methods.

However, it is apparent that it is necessary to further improve theresistance to ageing of coloured bituminous materials in order toprevent their degradation, including even under extreme climaticconditions.

SUMMARY OF THE INVENTION

Firstly the invention relates to a new composition based on resin andpigments, for obtaining coloured bituminous materials.

The resin used has the particular property of having a restricted rangeof solubility.

The colouring composition is prepared by carrying out the followingsuccessive steps:

Firstly, the resin is dissolved in water and within its range ofsolubility. The percentages by weight of resin and of water in themixture obtained are between about 30 and 70% of resin and 30 and 70% ofwater. The mixture obtained is clear.

The additive that enables one to obtain a stable dispersion, is added tothe mixture. The quantity of additive is between about 0.5 and 3% of theweight of the resin.

The additive is a surfactant, the molecule of which includes a chainwith hydrophilic character and a chain with hydrophobic character. It isan amphiphilic type of product.

Then water is added to the mixture in solution in sufficient quantity tocause the resin to precipitate. In effect, because of the addition ofthe water, the resin is no longer within its range of solubility.

The additive allows the dispersion of the resin in the water to bestabilised, and when the water is added to the mixture prevents thesettling and the agglomeration of the precipitated particles of resinwhich would end up in a gel.

Finally, pigments are introduced into the mixture to obtain thecolouring composition according to the invention. The pigments are inpowder form with a particle size of between 0.5 and 50 μm. They are ofan organic or a mineral type.

The quantity of pigments is between 50 and 150% of the weight of theresin.

The colouring composition according to the invention therefore has:

between about 5 to 20% and preferably 15% by weight of a resin with arestricted solubility range

between about 5 to 40% and preferably 20% by weight of pigments,

between about 0.1 to 5% and preferably 1% by weight of an additive withrespectively hydrophilic and hydrophobic properties,

between about 90 to 60% and preferably 64% by weight of water.

The invention also relates to a method of obtaining coloured orpigmented bituminous materials.

This method consists first of all of applying, onto at least one surfaceof the fibrous material to be treated, the colouring composition thathas just been described.

The fibrous material is notably a cellulose based felt or a board. Itcan be in the dry state or may include water in an amount ranging up to60% by weight.

The composition can be applied notably by spraying with or withoutcompressed air, by coating the surface using at least one transferroller (made of foam for example) or by the deposition of a very thinfilm.

The thickness of the layer obtained corresponds to a coating weight ofdry material between about 25 to 130 g/m².

Within this range of values, the thickness of the layer of colouringcomposition is sufficient to colour the substrate and remains thinenough to allow subsequent penetration of the bitumen into the fibrousmaterial.

The coloured fibrous material is then dried, notably by simple drying inair. It is finally subjected to a bitumen impregnation operation, thelayer of colouring composition undergoing curing at high temperature,within the mass of hot bitumen.

The bituminous material obtained has colouring on its surface. Testscarried out have shown that this colouring has better appearance andresistance compared with that provided using traditional colouringmethods.

DETAILED DESCRIPTION OF THE INVENTION

The invention will be better understood on reading the examples of itsimplementation that will now be described.

EXAMPLE 1

A colouring composition is prepared according to the invention, from aresin sold under the name of LAMAL® 141 S by the company LAMAL and whichis in the form of a powder with 100% dry material.

This resin is dissolved in water at ambient temperature and in equalproportions (50% by weight of resin and 50 by weight of water). Thesolution obtained is clear.

An additive of the type TEGOPREN® 5852H, sold by the company GOLDSCHMITis added to the mixture in an amount corresponding to about 2.5% of theweight of the resin. Then a quantity of water corresponding to 30% byweight of the mixture is added. The resin precipitates and a milkysolution of resin finely dispersed in water is obtained.

The pigments, in the form of a brown pigment paste sold by the companyHOLIDAY Dispersion are firmly added to the solution at the rate of 20%.

The colouring composition is applied onto one surface of a fibrousmaterial comprising 0 to 70% of water and then this is dried in the freeair.

It was observed that rubbing the coloured surface of the fibrousmaterial (notably with the finger) revealed no trace of pigmentwhatsoever.

EXAMPLE 2

A colouring composition according to the invention is prepared from aresin sold under the name LAMELITE® by the company AGROLINZ MELAMINITALIA and which is in the form of a powder.

This resin has a solubility in water between 30 and 65% at a temperatureof 25° C.

It is dissolved in the water in the following proportions: about 40% byweight of resin for 60% by weight of water.

An additive, sold under the name of TEGOPREN® 5852, is added to themixture in the quantity corresponding to about 4% by weight of theresin.

Water is then added to the mixture, in an amount corresponding to atleast 40% by weight of the mixture.

The pigments are finally incorporated into the mixture in the proportionof 50% (pigments/mixture, by weight). The pigments are in paste formwith about a 60% pigment content. The pigment is an ochre iron oxidepaste, sold under the name ASTRA® AGR 301.

The colouring composition is applied onto one surface of a fibrousmaterial that includes 0 to 70% of water and this is then dried in thefree air.

As was the case with the colouring composition conforming to Example 1,on rubbing the coloured surface of the fibrous material, no trace ofpigment appeared.

The two examples of a colouring composition according to the inventionwill now be compared with a colouring composition produced from a resinthat is totally soluble in water in all proportions.

This comparative colouring composition is produced from a resin soldunder the name of URECOLL MKS by the company BASF.

It is in the form of an aqueous solution comprising 70% by weight of drymaterials.

This resin is dissolved in water to provide a solution containing about20% of resin.

Pigments are incorporated into the mixture at the rate of about 130% ofthe weight of the resin.

This colouring composition is then applied onto one surface of thefibrous material that was also used in the examples according to theinvention and this is dried in the free air.

It is observed that, on rubbing the coloured surface of the materialwith the finger, this is coloured with pigment. Furthermore, if thematerial is dried by a forced: air dryer, this also causes loss ofgrains of pigment from the coloured surface of the material.

The comparison between Examples 1 and 2 and the colouring compositionbased on URECOLL® shows that it is essential to use a resin with reducedsolubility in water in order to improve the holding of the pigments onthe fibrous material.

The following explanations can be put forward without them being eitherexhaustive or definitive.

With the colouring composition according to the invention, a largeproportion of the resin envelops the pigments and is not dissolved inthe water. For Example 1, it is observed, for example, that only 20% byweight of the resin is dissolved.

Hence, a large proportion of resin remains on the surface of the fibrousmaterial which has been coated with a layer of colouring composition andthis allows the pigments to be attached to the material.

Contrary to this, when a colouring composition based on URECELL® isapplied, whatever the respective proportions of resin and water, theresin will difffuse into the fibrous material and the pigments will notbe fixed to the material.

Ageing tests have also been carried out on fibrous materials coated withthe colouring composition conforming to Example 1 and impregnated withbitumen and on fibrous materials coated with the comparative colouringcomposition based on URECOLL® resin and impregnated with bitumen.

The tests consisted of spraying water at a temperature of 35° C. inaccordance with the following steps:

3 weeks of spraying, day and night

2 weeks of alternating conditions: exposure to the sun during the dayand spraying at night.

3 weeks of no spraying: exposure to the sun and

finally 4 weeks of alternating conditions: exposure to the sun duringthe day and spraying at night.

Examination of the materials after these tests shows that thediscoloration of the materials coloured with the comparative colouringcomposition is greater than that of the materials coloured with thecomposition of Example 1.

It is also desirable to make the bituminous material more rigid in orderto make it more resistant to bowing or sagging.

To do this, it is known to incorporate into the fibrous material, beforeimpregnation with the bitumen, a resin at an amount ranging up to 4 to5% (indeed 10%) by weight of resin with respect to the weight of the drymaterial.

One may make reference to French Patent No. 2 466 489 which describes aprocess of this type.

At the time of the incorporation of the resin, the fibrous materialincludes from 0 to 70% water.

After the application of the resin, the material is dried, thenimpregnated with bitumen, in accordance with the usual methods.

The resin is incorporated onto the surface of the fibrous materialopposite to that which is or which will be coated with a colouringcomposition according to the invention.

The quantity of resin which is used in this process is relatively large.

However, it is apparent that by choosing a particular resin, thequantity of resin can be considerably reduced, while improving theresistance to bowing or sagging of the bituminous material.

The resin which is used in this case is a resin that is totally solublein water in all proportions.

With such a resin, it is sufficient to incorporate into the fibrousmaterial, a quantity of resin which is 2% by weight with respect to theweight of dry material. The maximum quantity of resin will be 10% byweight with respect to the weight of dry material.

By way of example, the previously described resin URECOLL®, can be used.

Tests have demonstrated that a quantity of resin 2% by weight withrespect to the weight of dry material, improves the resistance todeformation of the bituminous material in a damp environment by 50%.

Quite clearly, by incorporating more resin, the resistance will be evenmore improved.

Contrary to this, if an undissolved resin is incorporated into thefibrous material, no improvement in the resistance to deformation isobserved.

By way of an example, this is notably the case for the resin LAMAL®141S, previously described, diluted to 20% in water (that is to say,outside its solubility range) and used at the same quantity of 2% byweight with respect to the weight of fibrous material.

The dissolution of the resin in water is therefore essential so that theresin difffuses throughout the thickness of fibrous material. In thecontrary case, the solid particles of resin are filtered by the materialand remain on its surface without penetrating.

Hence, onto one and the same fibrous material, a colouring compositionaccording to the invention can be applied onto one face and a resindiluted with water onto the other face, this latter resin being totallysoluble in water in all proportions, and the quantity of resin used mayalso be as low as 2% by weight with respect to the weight of the dryfibrous material.

This fibrous material is then dried and impregnated with bitumen.

The bituminous material obtained has colour holding properties andresistance to bowing or sagging in a damp environment which areconsiderably improved.

What is claimed is:
 1. A method of preparing a colouring compositionwhich comprises the following successive steps:dissolving a first resinin water within its restricted range of solubility in proportions byweight of between about 30 and 70% of resin and 30 to 70% of water so asto obtain a mixture; adding to the mixture, an additive having both ahydrophilic and a hydrophobic character, at a rate of between 0.5 and 3%by weight of the resin; adding water in sufficient quantity to cause thefirst resin to precipitate; and adding pigments in powder form and at arate of between 50 and 150% by weight of the resin in order to obtainthe colouring composition.
 2. The method according to claim 1, whereinthe additive is a surfactant whose molecule includes a chain ofhydrophilic character and a chain of hydrophobic character.
 3. Themethod according to claim 1, wherein the pigments have a particle sizeranging between 0.5 and 50 μm.
 4. A method of obtaining a colouredbituminous material, which comprises:applying onto at least one face ofa material to be treated, a coating of the colouring compositionobtained according to the method of claim 1, so as to obtain a materialcoated with the colouring composition; drying the material coated withthe colouring composition so as to obtain a dried coated material; andimpregnating the dried coated material with bitumen.
 5. The methodaccording to claim 4, wherein the material is a cellulose based felt ora board.
 6. The method according to claim 4, wherein the coating of thecolouring composition has a coating weight of dry material rangingbetween about 25 and 130 g/m².
 7. The method according to claim 4,further comprising applying onto a face of the material that is notcoated with the colouring composition, an aqueous solution of a secondresin.
 8. The method according to claim 7, wherein said second resin istotally soluble in water in all proportions.
 9. The method according toclaim 7, wherein the second resin is applied in an amount rangingbetween 2 and 10% by weight with respect to the weight of dry material.